<img src="img-en.jpg" id="isOneWithAttribute" data-track-content/>
<img src="img-en.jpg" id="isOneWithClass" class="piwikTrackContent"/>
<!-- next content block tests it will find block only once although attribute and class is used -->
<div><a href="http://www.example.com" data-track-content class="piwikTrackContent"><img src="img-en.jpg" data-content-piece/><div id="innerNode"></div></a></div>
<div></div>
<div id="containsOneWithAttribute">
    <div>
        <div data-track-content><input type="submit"/></div>
    </div>
</div>